Field of Endeavor
The present application relates to additive manufacturing and more particularly to additive manufacturing fibre-reinforced polymer (FRP).
State of Technology
This section provides background information related to the present disclosure which is not necessarily prior art.
U.S. Pat. No. 6,299,810 for a method for manufacturing a carbon fiber composite provides the state of technology information reproduced below.
In a first embodiment of the invention, a series of carbon fibers are fed from a creel to a lathe of a winding assembly. The size or tow of the carbon fibers typically is in the range of 1,000 to 50,000 (i.e. 1,000 to 50,000 individual strands per bundle or tow) and generally between 5 to 20 spools are used to feed fibers of varying sizes to the winding assembly. The winding assembly includes a lathe having an elongated collection trough or basin, and a carriage that is reciprocably movable along the length of the trough. The carbon fibers are fed to the carriage, which includes a wetting jig under which the fibers are passed for applying a resin material to the fibers. The resin material flows through drip openings in the wetting jig and onto the fibers, substantially coating or soaking the fibers with the resin material. The carriage is mounted along a track that extends along the length of the lathe to enable the carriage to be reciprocably movable longitudinally along the length of the lathe. A carriage motor such as a servo motor or similar variable speed reversible motor is mounted at one end of the track to control the movement of the carriage therealong and is linked to a computer control which can be programmed to vary the speed and movement of the carriage along the track, as well as to cause the cariage to pause randomly during its travel along the length of the lathe.
The lathe further includes a main rotary drive motor mounted at the head-stock end of the lathe. The main drive motor typically is a variable speed reversible electric motor, such as a servo motor, and is inked to the same computer control for the carriage motor, which controls the motor so as to operate the drive motor at varying speeds. A mandrel is received within the collection trough, connected to the drive shaft of the drive motor and is rotated by the main rotary drive motor. The mandrel generally is approximately 12 to 20 feet in length and approximately 14 to 65 inches in width, although mandrels of other, varying sizes also can be used as desired. The mandrel generally includes an outer skin or side wall and first and second ends, mounted to the drive shaft and an idler shaft of the lathe, respectively. Heating elements such as heating tapes are generally mounted within the mandrel for internally heating the skin of the mandrel during curing of the resin material. A release agent such as a plastic film, including a nylon or polyethylene film or a non-stick coating such as a water or oil-based spray solvent-based silanes, and organic waxes, or similar agent is applied to the skin of the mandrel, covering the skin and the first and second ends of the mandrel to prevent the resin material from adhering to the mandrel as the carbon fibers are wound thereabout.
As the mandrel is rotated by the lathe, the carbon fibers, with the resin material applied thereto, are wound about the mandrel as the carriage is moved longitudinally along the track in a reciprocal movement to form a weave or sample about the mandrel. Generally, in most conventional processes for forming carbon fiber composites, the speed of the carriage and rotation of the mandrel is rigidly controlled to form the weave or sample with a very precise, exact pattern. In the present invention, however, as the carbon fiber weave or sample is formed, the speed and movement of the carniage is intentionally randomly varied, including pausing or varying the movement of the carriage along the lathe assembly. In addition, other elements of “chaos” such as varying the number of and size of the fibers, varying the amount of resin material applied to the fibers, adding hard and soft pieces or loose fibers onto the mandrel, modifying the outer skin of the mandrel to change to topography of the weave, varying the speed, pitch and tension of the winding of the fibers about the mandrel, and other actions are introduced so as to break up or physically disrupt any pattern to the weave. These physical disruptions or variations during the formation of the weave provide the resultant composite material with a random, or non-uniform, highly unique cross section and a decorative appearance upon finishing.
After a sufficient desired quantity or thickness of the weave has been wound, the mandrel is removed from the lathe assembly and placed within a vacuum chamber. In one preferred embodiment, the vacuum chamber includes an elongated tube, typically formed from steel and having an inner chamber having a sliding tray that is movable along skids or rollers into and out of the vacuum chamber. An upper mold plate is positioned over the tray and is movable toward and away from the tray, into and out of pressurized engagement with the weave or sample, while the tray finctions as a lower or bottom mold plate. Thus, as the upper mold plate is moved downwardly, the weave is compressed between the two mold plates. An air bladder or other compression device is mounted within the vacuum chamber and is positioned above and mounted to the upper mold plate. The bladder generally is an inflatable air bladder made from a durable, high strength reinforced silicone rubber material, such as AMS 3320G, manufactured by GE. Upon inflation of the bladder, the upper mold plate is urged downwardly into engagement with the sample so as to apply substantially even pressure along the length of the sample within the tray.
The sample is initially vacuumed to remove any air, voids and resin mixture VOCS, are bubbles or pockets, and is monitored to detect a rise in temperature generally of up to 100.degree. F.-120.degree. F. or as needed depending on resin type, time to cure and various other factors, indicating the resin is starting to cure. Thereafter, the bladder is inflated to apply pressure of approximately 5 to 65 psi to the sample while the vacuum is continued. At the same fime, the sample is heated to approximately 200.degree.-220.degree. F. for approximately two hours and until the resin material has cured. The temperature and amount of pressure can further be varied depending on the type of resin used. The application of the vacuum and pressure from the bladder causes the fibers to shift and move, further enhancing the effects of the physical disruptions to the pattern of the sample to cause the sample to be formed with a non-uniform cross-section and topography.
After the carbon fiber weave or sample has been compressed and cured, leaving a substantially solid composite material, the sample is removed from the vacuum chamber, cooled and thereafter is cut off of the mandrel to form elongated planks or sheets of carbon fiber composite. The planks or sheets of carbon fiber composite then are put through a finishing process including planing the composite sheets, cutting the sheets into sections and then sanding and assembling the sections into a variety of products.